I ran the math and I was sad.

The population of the world is 6, 894, 594, 844.
Assuming that a zombie virus was airborne, waterborne, and spread through bites and
scratches then only the few who were immune would survive.
A reasonable percentage of humans who are immune to an apocalyptic virus would be 3. 1%.
This means that 6, 894, 595 people would be immune to the virus.
This means to eliminate Every zombie each person would have to kill 999 zombies.
If each person killed one zombie per day it would take less than three years to eliminate Every
last zombie.
After this event was over it would take 17 generations of repopulating to bring the worlds
population back up to 6, 894, 594, 844.

Multiplayer on zombies maps would be legit. I haven't heard crap about black ops 2, but if they can make 8 players and vehicles work in zombies that wouldn't **** it up, I will happily protect my virginity gaming for the majority of my days.

Hey Diseases,
My name is Madagascar, and I hate every single one of you. All of you are weak, highly detectable viruses who spend every second of your day looking for ways to spread. You are everything bad in the world. Honestly, have any of you ever infected a water supply? I mean, I guess it's fun trying to make everyone vomit, hemorrhage and become depressed, but you all take to a whole new level. This is even worse than wasting evolution points on increasing your heat, moisture and cold resistance to level 4.

Don't be a stranger. Just hit me with your best epidemic. I'm pretty much healthy. I’m the fourth largest island in the world, and only have one port. What symptoms do you have, other than "fatigue" and "sores"? I also get no reports of infections, and have a banging hot port (She just shut down; **** was SO closed). You are all faggots who should just be vaccinated. Thanks for listening.
Pic Related: It's me and my port.

Assuming .1% are immune, you are missing one important point.
No zombie will bite a human and say "Oh damn, he's immune, let's go somewhere else, guys." There will be casualties, and a lot of them.
I'm going to go ahead and round the world's population to 7 billion, since it's all speculation.
That means that ~7 million will be immune.

It is safe to assume that 20% will die in the initial attacks. In fact, that is probably being too generous. This leaves us with 5.6 million immune survivors.

People that won't be as efficient in fighting:
Elderly: ~14% are age 65+
Children: ~24% are ages 0-17
So that means that 2128000 survivors won't be as efficient in fighting zombies, meaning that the adult survivors (3472000) will have to take that load, increasing the strain.

Some other facts to consider:
1) These are survivors all around the world. They are not united. They have no government. They have no leadership, and no contact. They will not be as efficient.
2) They are not necessarily "survival" types. Most survivors will die off due to malnutrition.
3) With hospitals closed down and medical supplies scarce, there will be an increase of other diseases.

In an ideal world, all survivors will be giant, Russian Bear Calvary type men and women, from ages 18-30, who are able to fight, and are willing to unite to defend themselves. In reality, you're going to get a **** load of hippies, businessmen, grandmothers, and idiots who will leeroy jenkins themselves to hell.

Lowes.
Theres already a garden, theres materials to set up defense, you have enough supplies to build a windmill ontop of the lowes. There is a parking lot that can easily be made into a walled off courtyard where work can be done. The plumbing could work for a week maybe and typically Lowes is surrounded by other hardware stores and clothing outlets and occasionally restraunts and general stores. Not to mention the gas station down the road.

When the apocalypse happens immediately alert everyone you know to head to one of these lowes, take all supplies possible in your vehicles, block off the front entrances to only allow 1 person in at a time and check every person head to toe for bites. Lack of privacy is ensued but protection is garaunteed.

Plenty of melee weapons for everyone and plenty of materials to turn into important devices in normal life. And not to mention, security.

Not saying that you'll be useless, but you don't have access to materials that older people would. A plan doesn't mean much if you aren't prepared ahead of time.

Good preparation questions:
What weapons do you have stockpiled?
How much ammunition do you have stockpiled?
How proficient with those weapons are you?
Do you have easily preserved food?
What about spare medical supplies?
What about transportation?
What about a guaranteed safehouse in a safe location, away from civilization?

I'm 19, and I have already accepted that I will probably be infected early on and devour everyone I care about. Yeah, I have plans, but that doesn't mean that I will survive.

About the gun; if the gun was silenced it wouldn't typically draw any attention in your direction, and bullets are far more common and are smaller and thus easy to carry. Also, guns can fire multiple shots before needing to be reloaded, which isn't the case for most crossbows.

I didn't necessarily mean guns when I said weapons and ammunition, but here are a few weapons-related questions you still would need to answer.
1) Do you have a crossbow?
2) Do you have an ample supply of bolts?
3) Crossbows aren't as simple as point-and-shoot, so do you have training with one?
4) Do you have the skills with a knife to fashion new bolts?
Also, why would you stay in or near a city, and why would you want a large group of survivors? An average city has several million people living in it in close quarters, leaving a lot of room for infection. If you keep emergency supplies, even basic supplies like you would keep for a hurricane or being snowed in, you can grab those and get out, once the initial shock wears off.

Some other points:
Food will be a primary target for looters. Why would you assume that there would be any left in stores? Same for medical supplies. Those are easily purchased now, so why wait for any disaster to happen. No sense waiting until after the world has gone to hell to have a stockpile of medical supplies or preservable foods.
Also, you may be a qualified mechanic, but that doesn't mean that you ejaculate gas and car parts. Again, that means preparation.

I'm not trying to argue. I'm just saying that raiding the nearest wal-mart and running isn't a sensible plan.

Also a point that's being missed is the initial spread. Even an airborne or waterborne disease would be quickly dealt with, and the area closed off. A disease spreading massively around the entire world is quite unlikely.

Yeah, but the most realistic zombie apocalypse to date seems to be the Max Brooks World War Z apocalypse. Nobody is immune, but it ONLY transmits through vital fluid contact. Therefore smart, capable people will survive. And although this may come as a surprise, there are more than you would think. Governments would not collapse, more likely the opposite. Humans are social creatures, we would bond together. Governments would unite their military forces and quickly train them on the weaknesses of the supposed zombies. In a few years or so, zombie levels would drop to the point where we could start to take back land, perhaps even cities.
In about 10 years, the zombies would either have rotted or we would have united to the point where we could unite trade lines again. Wouldn't take long after that.

No. OP doesn't know much about medicine. Once the virus enters ones's system, they are screwed. Naturally immunity to a virus is more like one in million, and about the same for bacteria. Bacteria can be fought with antibiotics and viruses by antivirals, but this won't save many people due to the chaos and lack of information on the disease. Immunity and treatment will play a very minimal role in who survives; rather, (considering it's multitude of routes of infection) isolationism and self sufficiency will determine survivors. People who have stockpiles of drugs, purified water through intense boiling and condensation, barricades, and air seals would survive. We will take my incredibly generous number of naturally immune people (7000) and couple it with people in the world who meet the isolation requirements before the breakout (10000 tops) to leave us with 17,000 survivors and 6,999,983,000 infected. You have to remember that this is before suicide and panic. We could fairly reasonably say that anyone not bunkered down before the outbreak would die. The human race would likely never recover, and any shred of social order will be obliterated. There would be no chance at all.

It is not a virus it makes more sense to be a parasite.
A virus would require you to be alive and warm to survive, a parasite however does not always require this.
A parasite will live inside you feasting on the food you ate in your stomach, then once you die it will dig its way to your brain and take control of you, and reviving your basic human needs such as eating so that it may continue to survive.
The transition of the parasite can either be airborne spores, or it lays eggs which it then plants into its victims through the saliva when it bites.
So, the surviving population will start off quite high and slowly drop at first and then topple out of control once they begin to swarm all over.